Control apparatus for hydraulically operated consumers

ABSTRACT

Apparatus which controls the flow of pressurized hydraulic fluid from a pump to a primary consumer or to a secondary consumer and from the primary consumer to the tank has a distributor valve whose spool changes its position in response to changes of fluid pressure in a control chamber wherein the fluid pressure is controlled by a pilot valve which can be actuated manually, electrically or by means of a fluid. A check valve which is interposed between the distributor valve and the primary consumer controls the speed of movement of the spool of the distributor valve to that position in which the primary consumer receives fluid. The secondary consumer receives fluid whenever the primary consumer is sealed from the pump. A further pilot-controlled valve is provided to control the flow of fluid from the primary consumer to the tank.

1451 Sept. 23, 1975 CONTROL APPARATUS FOR HYDRAULICALLY OPERATEDCONSUMERS Friedrich-Wilhelm Hiifer, Hofingen, Germany [73] Assignee:Robert Bosch G.m.b.H., Stuttgart,

Germany [22] Filed: June 4, 1973 [21] Appl. No.: 367,012

[75] Inventor:

[30] Foreign Application Priority Data July 5, 1972 Germany 2232857 [52]US. Cl. 91/413; 91/459; 91/461 [51] Int. Cl. F15B 11/16 [58] Field ofSearch 91/412, 461,413, 304, 91/459, 275, 361; 60/422, 427, 484; 251/43,

[56] References Cited UNITED STATES PATENTS 822,306 6/1906 Sanger 251/423,437,102 4/1969 Hamilton 91/461 X 3,465,519 9/1969 McAlvay et al.60/422 3,646,851 3/1972 Mohri.... 91/461 X 3,654,837 4 1972 Knapp 91/4613,662,548 5/1972 Suzuki et a1. 91/412 X 3,789,739 2/1974 Krehbiel et alv91/461 OTHER PUBLICATIONS U.S. ReRe-26, 523, F. H. Tennis, Feb. 11,1969.

Primary Examiner-Irwin C, Cohen Assistant Examiner Edward Look Attorney,Agent, or FirmMichael S. Striker [5 7] ABSTRACT Apparatus which controlsthe: flow of pressurized hydraulic fluid from a pump to a. primaryconsumer or to a secondary consumer and from the primary consumer to thetank has a distributor valve whose spool changes its position inresponse to changes of fluid pressure in a control chamber wherein thefluid pressure is controlled by a pilot valve which can be actuatedmanually, electrically or by means of a fluid. A check valve which isinterposed between the distribu tor valve and the primary consumercontrols the speed of movement of the spool of the distributor valve tothat position in which the primary consumer receives fluid. Thesecondary consumer receives fluid when ever the primary consumer issealed from the pump. A further pilot-controlled valve is provided tocontrol the flow of fluid from the primary consumer to the tank.

14 Claims, 3 Drawing Figures SOLENOIDS FLUID CONSUMER US Patent Sept.23,1975 Sheet 1 of 3 3,906,838

F l g .1

W SEC SOLENOIDS FLUID CONSUMER US Patent Sept. 23,1975 Sheet 2 of33,906,838

FLUID CONSUMER US Patent Sept. 23,1975 Sheet 3 01 3 3,906,838

49" SOURCE OF PRESSURE FLUID FLUID CONSUMER CONTROL APPARATUS FORHYDRAULICALLY OPERATED CONSUMERS BACKGROUND OF THE INVENTION The presentinvention relates to control apparatus for hydraulically operatedconsumers, and more particularly to improvements in control apparatusfor plural consumers of pressurized hydraulic fluid. Still moreparticularly, the invention relates to improvements in control apparatuswhich may be utilized to regulate the flow of fluid to and/or from oneor more consumers which are mounted on or pulled by an automotivevehicle, especially a tractor or a similar towing vehicle foragricultural implements.

German Offcnlegungsschrift No. 2,034,214 discloses a control apparatuswherein a consumer can receive pressurized hydraulic fluid by way of apilot-operated distributor valve and a check valve. The valve member ofthe distributor valve is movable relative to its housing in response toadmission of pressurized fluid into or in response to evacuation ofpressurized fluid from a control chamber at one axial end of the valvemember. The control chamber can be connected with the tank by way of aflow restrictor which is adjustable so that the rate of fluid flow fromthe control chamber decreases in response to movement of the valvemember toward one of its end positions. The pilot valve for thedistributor valve is actuatable by mechanical means and the valve memberof the distributor valve can assume three different positions includinga neutral position in which pressurized fluid flows from the pump backto the tank, a second position in which the pressurized fluid is free toflow from the pump to a consumer, and a third position in which thefluid can flow from the consumer to the tank. In order to prevent theflow of fluid to the consumer at a maximum rate in immediate response tomovement of the valve member to its second position, the controlapparatus comprises a special switchover device which connects theaforementioned control chamber with the tank in such a way that theresistance to flow of fluid from the control chamber into the tankincreases while the valve member approaches its second position. Theswitchover device is controlled by fluid pressure at the inlet andoutlet of the control apparatus. The result is that the rate of flow ofpressurized fluid to the consumer increases gradually in order to avoidundesirable pressure peaks.

A drawback of the just described control apparatus is that it comprisesa substantial number of complex and expensive parts and that it is notsufficiently versatile to serve as a means for regulating the flow ofpressurized fluid to or from several consumers. Also, the pressurizedfluid which is circulated in the neutral position and/or third positionof the valve member is wasted.

SUMMARY OF THE INVENTION An object of the invention is to provide anovel and improved apparatus for controlling the flow of pressurizedfluid to several discrete consumers.

Another object of the invention is to provide a control apparatuswherein the fluid which is being pressurized by a pump or the like isused with greater economy and with less leakage than in heretofore knownapparatus.

A further object of the invention is to provide a control apparatuswhich can be designed for preferential flow of fluid to a selected oneof several consumers of pressurized hydraulic fluid.

An additional object of the invention is to provide the controlapparatus with novel means for regulating the speed of movement of oneor more parts (such as valve members) which determine the rate of fluidflow to or from one or more consumers.

An ancillary object of the invention is to provide a control apparatuswherein the aforementioned speed regulating action is largelyindependent from the rate of fluid flow and/or from the pressure offluid.

The invention is embodied in an apparatus for controlling the flow ofpressurized hydraulic fluid to first and second consumers, particularlyto consumers (such as hydraulic cylinder and piston units, jacks,motors, valves or the like) mounted on or towed by an agriculturalvehicle (e.g., a tractor). The apparatus comprises a pump or ananalogous source: of pressurized hydraulic fluid, means defining aninlet connected with the pump and first and second outlets respectivelyconnected with the first and second consumers, a reservoir whichcollects spent fluid and provides a supply for the pump, and adistributor valve interposed between the inlet and the two outlets andhaving a reciprocable spool or an analogous valve member movable betweena plurality of positions including a predetermined position in whichpressurized fluid is free: to flow toward the first outlet. The valvemember is further arranged to establish a path for the flow of fluidfrom the inlet to the second outlet in at least some of its positions,and the apparatus further comprises regulating means for initiating themovements of the valve member and for controlling the speed of movementof the valve member toward the predetermined position. The regulatingmeans includes means defining a control chamber, pilot valve means whichis actuatable to connect the control chamber with the reservoir or withthe pump to thereby respectively effect the movement of the valve memberto and from the predetermined position, and check valve means interposedbetween the distributor valve and the first outlet and having means forreducing the rate of fluid flow from the control chamber to thereservoir during opening of the check valve means and while the pilotvalve means connects the control chamber with the reservoir.

The fluid pressure in the control chamber preferably equals the fluidpressure at the second outlet in the other positions of the valvemember, i.e., when the valve member permits pressurized fluid to flowfrom the inlet to the second outlet.

The regulating means is preferably provided with bore means whichconnects the pilot valve means with the control chamber, and the meansfor reducing the rate of fluid flow from the control chamber maycomprise a second valve member which forms part of the check valve meansand is movable from a sealing position (in which the inlet is sealed romthe first outlet) toward an open position to thereby interrupt or atleast substantially reduce the flow of fluid from the control chamber byway of the bore means. The arrangement may be such that, when the secondvalve means seals the bore means, the fluid can still flow from thecontrol chamber to the reservoir by way of a fixed flow restrictor.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved control apparatus itself, however, both as to its constructionand its mode of operation, together with additional features andadvantages thereof, will be best understood upon perusal of thefollowing detailed description of certain specific embodiments withreference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partly diagrammaticsectional view of a control apparatus for the flow of fluid to twohydraulically operated consumers which embodies one form of theinvention and which employs two solenoidoperated pilot valves;

FIG. 2 is a similar view of a second control apparatus which employs twomechanically operated pilot valves; and

FIG. 3 is a similar view of a third control apparatus which employs twofluid-operated pilot valves.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1,there is shown a control apparatus having a housing or body whichcomprises two units or sections, namely a main unit or section 1 and apilot unit or section 2. The main section 1 is provided with an inlet orpressure channel 3 which is connected with a supply conduit 5 foradmission of pressurized hydraulic fluid from a suitable source, such asa pump 4. The pump 4 draws fluid from a reservoir or tank 6. A branchline 7 which communicates with the inlet 3 contains a safety valve hereshown as a pressure relief valve 9. When the valve 9 is open, the branchline 7 communicates with a return conduit 8 which discharges fluid intothe tank 6.

The main housing section 1 is further provided with an elongated bore 11for the valve member or spool 13 ofa distributor valve 12. The purposeof the distributor valve 12 is to switch over from admission ofpressurized fluid to a first or primary consumer 35 to admission ofpressurized fluid to a second or auxiliary consumer 20, or vice versa.The bore 11 for the spool 13 communicates with several grooves which aremachined into the main section 1. These grooves include a first annulargroove which communicates with the inlet 3. In the illustrated axialposition of the spool 13, the groove 10 communicates with a secondannular groove 18 which admits pressurized fluid to a channel 19constituting an outlet for admission of pressurized fluid to theauxiliary consumer 20. A land or piston 17 of the spool 13 is shown asbeing located intermediate the two axial ends of the groove 10 so thatthe fluid can flow from the inlet 3 to the outlet 19. The piston 17 isbounded by two concentric grooves and 16 machined into the peripheralsurface of the spool 13. The latter is permanently biased in a directionto the right, as viewed in FIG. 1, by a helical spring 14 which isinstalled in the left-hand end portion of the bore 11. The auxiliaryconsumer 20 is assumed to constitute a distributor valvewhich can admitpressurized fluid to the motor of a harvester or to the motor of awinch, not shown.

The main housing section 1 is further provided with a third annulargroove 21 which is located to the left of the groove 10 and communicateswith the axial bore 11. The groove 21 can admit pressurized fluid to achannel 22. The piston 17 of the spool 13 is provided with one or moreaxially parallel notches 17 whose depth increases in a direction fromthe groove l5 toward the groove 16 and which serve for accurateregulation of the flow of fluid from the inlet 3 to the outlet 19. Thatend portion of the bore 11 which receives the helical spring 14communicates with the return conduit 8 by way ofa channel 8a so that thepressure in this end portion of the bore 11 equals atmospheric pressure.

A further annular groove 24a in the housing of the main unit 1 formspart of a control chamber 23 which is adjacent to the right-hand axialend of the spool 13. The rightmost portion 24 of the control chamber 23constitutes a cylinder chamber which can receive the adjacent right-handend portion of the spool 13 when the spring 14 is free to expand. Theright-hand end portion of the spool 13 is provided with one or moreflowrestricting notches 25 which control the rate of fluid flow from thecylinder chamber 24 into the groove 24a while the spool 13 moves underthe action of the spring 14.

The pilot section 2 of the housing is sealingly connected with the mainsection 1 and is formed with a channel or bore 29 which extends into themain section 1 and communicates with the groove 24a. That portion of thechannel or bore 29 which is provided in the main section 1 contains afixed flow restrictor 30 offering a predetermined resistance to the flowof fluid therethrough. The righthand end of the channel 29 communicateswith an enlarged portion of a bore provided in the pilot section 2 for apressure relieved 3-position 2-way pilot valve 27. This pilot valvecomprises a valve member 27a, a solenoid 26 which can be energized tomove the valve member 27a downwardly, as viewed in FIG. 1, and a helicalspring 27b which biases the valve member 27a upwardly. The lowermostpart of the bore for the valve member 27a of the pilot valve 27communicates with a return line or channel 31 which is machined in partinto the pilot section 2 and in part into the main section 1 andcommunicates with a discharge opening 31a connected to the returnconduit 8 so that the fluid issuing from the opening 31a can return intothe tank 6. In the illustrated axial position of the valve member 27a(solenoid 26 deenergized), the pilot valve 27 connects the channel orbore 29 with a branch line 28 which communicates with the inlet 3. Thus,when the spring 27b is free to expand, the pilot valve 27 allows fluidto flow from the pump 4 into the control chamber 23 by way of the supplyconduit 5, inlet 3, branch line 28, the bore for the valve member 27a,channel or bore 29 and fixed flow restrictor 30.

The aforementioned channel 22 communicates with a blind bore 39 which ismachined into the main section 1 and receives a check valve or one-wayvalve 32 serving to directly control the admission of pressurized fluidt0 the primary consumer 35. When the check valve 32 is open, pressurizedfluid can flow from the channel 22 into an outlet 33, which is machinedinto the main section 1, and thence to the primary consumer 35 by way ofa working line 34. The primary consumer 35 comprises a cylinder 35a, apiston 35b and a piston rod 35c. The piston rod 35c is assumed to beconnected to the table of a harvester forming part of a harvesterthresher (not shown) so that the table rises when the chamber 35d of thecylinder 35a receives pressurized fluid.

The check valve 32 comprises a conical valve member 36 which is biasedagainst a seat in the main section 1 by a helical spring 38. The valvemember 36 has an extension or plunger 37 which is reciprocable in theblind bore 39 and is provided with a circumferential groove 40. When theextension 37 assumes the axial position shown in FIG. 1, i.e., when thecheck valve 32 is closed, the pressurized fluid which flows in thechannel or bore 29 can bypass the flow restrictor 30 by flowing througha bore 41, through the groove 40, and thereupon through a further bore42 which discharges into the channel 29 downstream of the flowrestrictor 30. It will be seen that the extension 37 constitutes a meansfor changing the rate of fluid flow to or from the control chamber inresponse to movement of the valve member 36 in the bore 39.

The main section 1 further receives a fluiddischarging valve 44 whichcan be actuated to allow hydraulic fluid to flow from the chamber 35a ofthe cylinder 35a of the primary consumer 35 back into the tank 6. Thevalve member 45 of the discharging valve 44 has a conical portion 59which normally bears against a seat in the main section 1 under theaction of a helical spring 52. The conical portion 59 of the valvemember 45 then seals the discharge opening 31a from a channel 43, andthus from the outlet 33, as long as the valve 44 remains closed. Thevalve member 45 has an axially extending flow restricting bore 46 whichcan communicate with the return line 31 in response to opening of asecond pressure relieved pilot valve or shutoff valve 49 provided in thepilot section 2. The pilot valve 49 comprises a valve member 49a whichnormally engages a seat under the action of a spring 49b and can bedisplaced against the opposition of the spring 49b in response toenergization of a solenoid 48. When the solenoid 48 is energized, thevalve member 49a moves upwardly and thereby connects a pilot line 47with the return line 31. The valve member 45 is reciprocable in a bore50 provided in the main section 1. The right-hand portion of the bore 50constitutes a chamber which is filled with fluid and accommodates theaforementioned spring 52 and receives hydraulic fluid by way of a flowrestricting orifice 51 provided in a valve plate 53 which is biasedagainst an internal shoulder or seat of the valve member 45 by thespring 52. The valve plate 53 is received in a bore 54 of the valvemember 45. The orifice 51 allows fluid to escape from the right-hand endportion or chamber of the bore 50 when the valve member 45 is caused tomove in a direction to the right, as viewed in FIG. 1.

The means for actuating the pilot valves 27 and 49 of the pilot unit 2comprises a selector switch 55 having a handle 56. The median contact55c of the switch 55 is connected with an energy source 155 and can bemoved into engagement with a second contact 55a to thereby energize thesolenoid 26 or into engagement with a third contact 55b to therebycomplete the circuit of the solenoid 48. The handle 56 is accessible tothe operator of the control apparatus, for example to the driver of anagricultural tractor.

The operation is as follows:

When the handle 56 of the selector switch 55 is maintained in itscentral or neutral position, the median contact SSC is disengaged fromthe contacts 55a and 55b so that the solenoids 26 and 48 aredeenergized. Such position of the handle 56 corresponds to the neutralcondition or setting of the control apparatus. The pressurized fluidwhich is being furnished by the pump 4 flows from the supply conduit 5into the inlet 3 of the main section 1. The piston 17 of the spool 13 islocated between the grooves and 21 so that it seals the inlet 3 from thechannel 22 and outlet 33. The fluid can flow into the outlet 19 and tothe secondary consumer 20. The check valve 32 is closed so that itprevents the flow of fluid between the channel 22 and the outlet 33.

The fluid also flows from the inlet 3 into the branch line 28 and intothe bore for the valve member 27a of the pilot valve 27. The valvemember 27a allows such fluid to flow into the channel 29 and controlchamber 23 by way of the flow restrictor 30. At the same time, the fluidcan reach the control chamber 23 by way of the bores 41, 42 and groove40 in the extension 37 of the valve member 36. The fluid pressure in thecontrol chamber 23 suffices to maintain the spool 13 in the lefthand endposition in which the helical spring 14 stores energy and the piston 17seals the inlet 3 from the channel 22. The secondary consumer 20 canadmit pressurized fluid to one or more motors or other fluid consumingdevices, or returns the fluid into the tank 6. As mentioned before, thesecondary consumer 20 may constitute a distributor valve which can admitpressurized fluid to the motor of the harvester and/or to the motor of awinch. The pressure of fluid in the control chamber 23 equals thepressure at the outlet 19 when the pump 4 supplies pressurized fluid tothe consumer 20.

If the operator thereupon decides to raise the aforementioned table,i.e., to admit pressurized fluid to the chamber 35d of the cylinder 35aof the primary consumer 35, the handle 56 of the selector switch 55 ispivoted in a clockwise direction, as viewed in FIG. 1, so that themedian contact 55c engages the right-hand contact 55a and therebyenergizes the solenoid 26. The solenoid 26 displaces the valve member27a against the opposition of the spring 27b so that the pilot valve 27connects the channel or bore 29 with the return line 31 andsimultaneously seals the branch line 28 from the channel or bore 29.Therefore, pressurized fluid can flow from the control chamber 23 to thetank 6 and the spring 14 is free to expand so as to shift the spool in adirection to the right, i..e., toward the cylinder chamber 24. The spool13 then gradually reduces the rate of fluid flow from the inlet 3 to theoutlet 19 so that the secondary consumer 20 is ultimately shut off fromthe pump 4. At the same time, the inlet 3 begins to communicate with thegroove 21 and channel 22 to thereby increase the fluid pressure in theblind bore 39. When the pressure in the bore 39 exceeds the pressure inthe outlet 33 and the bias of the spring 38, the valve member 36 movesin a direction to the left, as viewed in FIG. I, and allows the fluid toflow from the channel 22 to the outlet 33 and into the working line 34and chamber 35d of the primary consumer 35. The extension 37 then shiftsthe groove 40 in a direction to the leftso that the bore 41 is sealedfrom the bore 42 and the fluid can flow from the control chamber 23 onlyby way of the fixed flow restrictor 30 in the channel or bore 29. Thisresults in a substantial deceleration of axial movement of the spool 13under the action of the helical spring 14, i.e., in substantialdeceleration of the spool 13 during movement to a predetermined positionin which the pump 4 supplies pressurized fluid to the outlet 33. Suchdeceleration of the valve member 13 takes place when the piston 17travels along the housing portion separating the grooves 10 and 18whereby the notch or notches l7',insulre gradual reduction of fluid flowfrom the inlet 3 into the outlet 19. A further deceleration of the spool13 against the action of the expanding spring 14 takes place when theright-hand end portion of the spool reaches the cylinder chamber 24. Asmentioned before, the outflow of fluid from the chamber 24 into thegroove 24a can take place only by way of the flow restricting notch ornotches 25 which thereby insure that the movement of the spool 13 intothe chamber 24 is gradual.

In the meantime, the valve member 36 is completely lifted off its seatin the main section 1 so that the valve 32 allows practicallyunobstructed flow of pressurized fluid from the channel 22 to theworking line 34 and chamber 35d. It will be noted that the primary consumer 35 has preference over the secondary consumer 20, i.e., that theconsumer is shut off from the pump 4 when the consumer 35 receivespressurized fluid.

When the piston rod 350 of the primary consumer 35 has lifted theaforementioned table or another load to a desired level, the operatormoves the handle 56 of the selector switch 55 back to the neutralposition in which the median contact 550 is disengaged from the contact55a. The solenoid 26 is deenergized and the valve member 27a of thepilot valve 27 is free to return to the illustrated position under theaction of the spring 27b. The pressurized fluid is again free to flowinto the control chamber 23 by way of the branch line 28 and chann'el orbore 29. Therefore, the spool 13 begins to move against the oppositionof the spring 14. The pressure in the channel 22 decreases so that thecheck valve 32 closes under the action of the spring 38 and preventsfurther flow of pressurized fluid to the chamber 35d of the primaryconsumer 35. At the same time, the fluid in the chamber 35d is entrappedso that the table which is supported by the piston rod 35c cannotdescend. The spool 13 then assumes an axial position in which the inlet3 communicates with the outlet 19 so that the secondary consumer 20 canreceive pressurized fluid.

If the operator thereupon desires to lower the load which is supportedby the piston rod 350 of the primary consumer 35, the handle 56 of theselector switch 55 is moved to the position shown in FIG. 1 so that thesolenoid 48 of the second pilot valve 49 is energized and moves thevalve member 49a against the opposition of the spring 49b. The cylinderchamber 35d then communicates with the tank 6 by way of the working line34, outlet 33, flow restricting bore 46 of the valve member 45, pilotline 47, return line 31 and discharge opening 31a. The orifice 46 actsas a flow restrictor so that the fluid pressure in the outlet 33 exceedsthe fluid pressure in the pilot line 47 whereby the valve member 45moves against the opposition of the spring 52 and connects the outlet 33directly with the discharge opening 31a. However, the rate at which thefluid can flow from the outlet 33 and directly into the dischargeopening 31a increases only gradually because the piston 45 can penetrateinto the bore 50 only to the extent which is determined by thecross-sectional area of the orifice 51 in the valve plate 53. Thisorifice 51 prevents an abrupt descent of the load which is supported bythe piston rod 350 of the primary consumer 35. The downward movement ofthe load which is supported by the piston rod 350 is interrupted as soonas the operator returns the handle 56 of the selector switch 55 to itsneutral position. This deenergizes the solenoid 48 so that the pilotvalve 49 closes to thus seal the pilot line 47 from the return line 31.Consequently, the pressure in the valve member 45 rises to match thepressure in the outlet 33 so that the spring 52 expands and returns theconical surface 59 of the valve member 45 into sealing engagement withits seat in the main section 1. When the pilot valve 49 closes inresponse to return movement of the handle 56 to its neutral position,the fluid which continues to flow from the outlet 33 via bore 46 movesthe valve plate 53 away from the shoulder or seat at the left-hand endof the bore 54 so that the right-hand end of the bore 50 can communicatewith the interior of the left-hand portion of the valve member 45 notonly by way of the orifice or orifices 51 but also by way of the spacesurrounding the lifted-off valve plate 53 which insures a practicallyinstantaneous return movement of the conical surface 59 into engagementwith its seat.

The secondary consumer 20 receives pressurized fluid by way of thesupply conduit 5, inlet 3, grooves 10, 16 and outlet 19 in the neutralas well as in the lefthand end positions of the handle 56.

The control chamber 23, pilot valve 27 and the check valve 32 togetherconstitute a regulating means which initiates the movements of the valvemember 13 and which also controls the speed of movement of the valvemember 13 toward its predetermined position in which the distributorvalve 12 and the check valve 32 cooperate to admit pressurized fluid tothe outlet 33. As mentioned before, the extension 37 of the valve member36 reduces the rate of fluid flow from the control chamber 23 to thereservoir 6 during opening of the check valve 32 by moving the groove 40out of register with the bores 41, 42 while the pilot valve 27 connectsthe control chamber 23 with the reservoir 6.

An important advantage of the improved control apparatus is that theoperator can rapidly shift from delivery of pressurized fluid to aselected one of several discrete consumers, that the delivery of fluidcan be shifted from delivery to outlet 19 to delivery to outlet 33 withlittle loss in time but with a gradual decrease of fluid flow to theoutlet 19, and that the braking of the valve member 13 is thendetermined by the fluid flowing to the outlet 33 for the primary orpreferred consumer 35.

The control apparatus of FIG. 2 is similar to that of FIG. 1 and,therefore, all such parts which are identical with or clearly analogousto the corresponding parts of the first apparatus are denoted by similarreference characters. The main difference is that the pilot valves 27and 49' do not employ solenoids; instead, the pilot section 62 of thehousing supports a rotary shaft 64 for a wiper 63 which can displace aninner end portion or follower 27A of the valve member 27a or an innerend portion or follower 49A of the valve member 49a. The shaft 64 can beprovided with a handle corresponding to the handle 56 of FIG. 1 or canbe moved clockwise or counterclockwise by remote control. If the shaft64 is connected with a handle, the latter is preferably movable relativeto a scale having graduations or other symbols which indicate themomentary angular position of the shaft 64 and wiper 63. FIG. 2 showsthe wiper 63 in its neutral position, i.e., the pilot valve 49' isclosed and the pilot valve 27 allows the branch line 28 to communicatewith the channel or bore 29. The chamber 35d receives pressurized fluidwhen the wiper 63 depresses the follower 27A, and the piston rod 350 canpenetrate into the cylinder 35a under the weight of the load (table)thereon when the wiper 63 depresses the follower 49A.

In all other respects the operation of the control apparatus of FIG. 2is identical with that of the first control apparatus.

The control apparatus of FIG. 3 is also similar to the apparatus ofFIG. 1. The main difference is that the se lcctor means for actuatingthe pilot valve 27" or 49" in the pilot section 72 of the housingcomprises a hydraulic or pneumatic selector device. As shown, the

valve member 49a of the pilot valve 49 will move to its open position inresponse to admission of pressurized fluid by way of a pipe 75, and thevalve member 27a" of the pilot valve 27" will seal the branch line 28from the channel or bore 29 in response to admission of pressurizedfluid by way of a pipe 76. The admission of pressurized fluid from asource 77 to the pipe 75 or 76 is regulated by a valve 78 which canconnect the pipe 75 with the source 77 when the pipe 76 is connected tothe tank 6, or vice versa. The valve 78 can further assume a neutralposition in which the tank 6 is connected with the pipes 75 and 76. Thefluid which is admitted from the source 77 via pipe 75 can act againstthe underside of a piston 73 on the valve mem' ber 49a, and the fluidwhich is admitted from the source 77 via pipe 76 can act against theupper side of a piston 74 forming part of the valve member 27a".

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featureswhich fairly constitute essential characteristics of the generic andspecific aspects of my contribution to the art and, therefore, suchadaptations should and are intended to be comprehended within themeaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent:

1. Apparatus for controlling the flow of pressurized hydraulic fluid tofluid consumer motors, particularly to consumer motors mounted on ortowed by an agricultural vehicle, comprising first and second consumermotors; a source of pressurized fluid; a housing including meansdefining an inlet connected to said source and first and second outletsrespectively connected with said first and second fluid consumer motors;a reservoir; a distributor valve interposed between said inlet and saidoutlets and having a valve member movable between a plurality ofpositions including a predetermined position in which pressurized fluidis free to flow from said inlet towards said first outlet, said valvemember being arranged to establish a path for the flow of fluid fromsaid inlet to said second outlet in at least some other positionsthereof; and regulating means for initiating the movements of said valvemember and for controlling the speed of movement of said valve membertoward said predetermined position, said regulating means comprising acontrol chamber, a pilot valve means actuatable to connect said chamberwith said reservoir or with said source to thereby respectively effect amovement of said valve member to and from said predetermined position,and check valve means inter posed between said distributor valve andsaid first outlet and movable between a closed position in which itprevents flow of pressurized fluid from said distributor valve to saidfirst outlet and an open position in which it permits flow ofpressurized fluid from said distributor valve to said first outlet, saidcheck valve means being biased to said closed position thereof and movedby prcssurizedfluid from said closed to said open position thereof whensaid valve member of said distributor valveiS in said predeterminedposition in which pressurized fluid is free to flow from said inletthrough said distributor valve towards said first outlet; and flowreducing means for reducing the rate of fluid flow from said controlchamber to said reservoir while said pilot valve means is actuated toconnect said control chamber with said reservoir, said flow reducingmeans being movable between an inoperative position in which it does notaffect the flow of fluid from said control chamber to said reservoir andan operative position in which it reduces the rate of flow of fluid fromsaid control chamber to said reservoir, said flow reducing means beingconnected to said check valve means in such a manner so as to be movedinto operative position when said check valve means is in open positionand to be moved into inoperative position when said check valve means isin closed position.

2. Apparatus as defined in claim 1, wherein said valve member comprisesmeans for gradually reducing the rate of fluid flow from said inlet tosaid second outlet during movement of said valve member toward saidpredetermined position.

3. Apparatus as defined in claim 2, wherein said means for graduallyreducing the rate of fluid flow to said second outlet comprises: apiston having at least one peripheral notch.

4. Apparatus as defined in claim 1, wherein said chamber comprises anormally fluid-filled portion into which a portion of said valve memberpenetrates to expel the fluid therefrom during the last stage ofmovement of said valve member to said predetermined position.

5. Apparatus as defined in claim 4, wherein said portion of said valvemember comprises flow restricting means for regulating the rate of fluidflow from said portion of said chamber during said last stage ofmovement of said valve member to said predetermined position.

6. Apparatus as defined in claim 1, wherein said pilot valve meanscomprises a pressure-relieved three-way two-position valve.

7. Apparatus as defined in claim 1, further comprising a passageconnecting said first consumer with said reservoir, normally closedfluid discharging valve means in said passage, and second pilot valvemeans actuatable to open said fluid discharging valve means in one ofsaid other positions of said valve member to thereby allow the fluid toflow from said first consumer to said reservoir.

8. Apparatus as defined in claim 7, wherein said fluid discharging valvemeans has a second valve member normally assuming a closed position andhaving a bore one end of which communicates with said first outlet andanother end of which communicates with said reservoir in response toactuation of said second pilot valve means whereby the pressuredifferential between said ends of said bore suffices to effect themovement of said second valve member from said closed position.

9. Apparatus as defined in claim 8, wherein said fluid discharging valvemeans comprises a housing having a fluid-filled second bore for saidsecond valve member, said second valve member having a passageconnecting said first mentioned bore with said second bore and saidfluid discharging valve means further comprising an apertured valveplate provided iii said second valve member to regulate the flow offluid into and from said second bore and means for biasing said valveplate against a seat provided therefor in said second valve member.

10. Apparatus as defined in claim 7, wherein said second pilot valvemeans comprises a pressure-relieved shut-off valve.

11. Apparatus as defined in claim 7, further comprising electricactuating means for at least one of said pilot valve means.

12. Apparatus as defined in claim 7, further comprising fluid-operatedactuating means for at least one of said pilot valve means.

13. Apparatus as defined in claim 7, further comprising mechanicalactuating means for at least one of said pilot valve means.

14. Apparatus as defined in claim 1, wherein said housing has a blindbore having an open end and defining a seat at said open end, andwherein said regulating means has bore means connecting said pilot valvemeans with said chamber and said means for reducing the rate of fluidflow from said chamber comprising a second valve member forming part ofsaid check valve means and movable from a sealing position engaging saidseat to thereby interrupt the flow of fluid in said bore means.

1. Apparatus for controlling the flow of pressurized hydraulic fluid tofluid consumer motors, particularly to consumer motors mounted on ortowed by an agricultural vehicle, comprising first and second consumermotors; a source of pressurized fluid; a housing including meansdefining an inlet connected to said sourcE and first and second outletsrespectively connected with said first and second fluid consumer motors;a reservoir; a distributor valve interposed between said inlet and saidoutlets and having a valve member movable between a plurality ofpositions including a predetermined position in which pressurized fluidis free to flow from said inlet towards said first outlet, said valvemember being arranged to establish a path for the flow of fluid fromsaid inlet to said second outlet in at least some other positionsthereof; and regulating means for initiating the movements of said valvemember and for controlling the speed of movement of said valve membertoward said predetermined position, said regulating means comprising acontrol chamber, a pilot valve means actuatable to connect said chamberwith said reservoir or with said source to thereby respectively effect amovement of said valve member to and from said predetermined position,and check valve means interposed between said distributor valve and saidfirst outlet and movable between a closed position in which it preventsflow of pressurized fluid from said distributor valve to said firstoutlet and an open position in which it permits flow of pressurizedfluid from said distributor valve to said first outlet, said check valvemeans being biased to said closed position thereof and moved bypressurized fluid from said closed to said open position thereof whensaid valve member of said distributor valve is in said predeterminedposition in which pressurized fluid is free to flow from said inletthrough said distributor valve towards said first outlet; and flowreducing means for reducing the rate of fluid flow from said controlchamber to said reservoir while said pilot valve means is actuated toconnect said control chamber with said reservoir, said flow reducingmeans being movable between an inoperative position in which it does notaffect the flow of fluid from said control chamber to said reservoir andan operative position in which it reduces the rate of flow of fluid fromsaid control chamber to said reservoir, said flow reducing means beingconnected to said check valve means in such a manner so as to be movedinto operative position when said check valve means is in open positionand to be moved into inoperative position when said check valve means isin closed position.
 2. Apparatus as defined in claim 1, wherein saidvalve member comprises means for gradually reducing the rate of fluidflow from said inlet to said second outlet during movement of said valvemember toward said predetermined position.
 3. Apparatus as defined inclaim 2, wherein said means for gradually reducing the rate of fluidflow to said second outlet comprises a piston having at least oneperipheral notch.
 4. Apparatus as defined in claim 1, wherein saidchamber comprises a normally fluid-filled portion into which a portionof said valve member penetrates to expel the fluid therefrom during thelast stage of movement of said valve member to said predeterminedposition.
 5. Apparatus as defined in claim 4, wherein said portion ofsaid valve member comprises flow restricting means for regulating therate of fluid flow from said portion of said chamber during said laststage of movement of said valve member to said predetermined position.6. Apparatus as defined in claim 1, wherein said pilot valve meanscomprises a pressure-relieved three-way two-position valve.
 7. Apparatusas defined in claim 1, further comprising a passage connecting saidfirst consumer with said reservoir, normally closed fluid dischargingvalve means in said passage, and second pilot valve means actuatable toopen said fluid discharging valve means in one of said other positionsof said valve member to thereby allow the fluid to flow from said firstconsumer to said reservoir.
 8. Apparatus as defined in claim 7, whereinsaid fluid discharging valve means has a second valve member normallyassuming a closed position and having a bore one enD of whichcommunicates with said first outlet and another end of whichcommunicates with said reservoir in response to actuation of said secondpilot valve means whereby the pressure differential between said ends ofsaid bore suffices to effect the movement of said second valve memberfrom said closed position.
 9. Apparatus as defined in claim 8, whereinsaid fluid discharging valve means comprises a housing having afluid-filled second bore for said second valve member, said second valvemember having a passage connecting said first mentioned bore with saidsecond bore and said fluid discharging valve means further comprising anapertured valve plate provided in said second valve member to regulatethe flow of fluid into and from said second bore and means for biasingsaid valve plate against a seat provided therefor in said second valvemember.
 10. Apparatus as defined in claim 7, wherein said second pilotvalve means comprises a pressure-relieved shut-off valve.
 11. Apparatusas defined in claim 7, further comprising electric actuating means forat least one of said pilot valve means.
 12. Apparatus as defined inclaim 7, further comprising fluid-operated actuating means for at leastone of said pilot valve means.
 13. Apparatus as defined in claim 7,further comprising mechanical actuating means for at least one of saidpilot valve means.
 14. Apparatus as defined in claim 1, wherein saidhousing has a blind bore having an open end and defining a seat at saidopen end, and wherein said regulating means has bore means connectingsaid pilot valve means with said chamber and said means for reducing therate of fluid flow from said chamber comprising a second valve memberforming part of said check valve means and movable from a sealingposition engaging said seat to thereby interrupt the flow of fluid insaid bore means.